Since 2018, specialist-prescribed medical cannabis has been legal in the UK....

https://tiny-wiki.win/index.php/Medical_Cannabis_for_Migraines_in_the_UK:_A_Patient%E2%80%99s_Guide_to_the_Pathway

Since 2018, specialist-prescribed medical cannabis has been legal in the UK. This guide explores eligibility after standard treatments, what consultations involve, and why NHS access is limited